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Anti-Proteinase 3 (PR3) Antibody (Serum) by Line Blot

Published: August 9, 2026Updated: August 16, 2026

This test detects antibodies against Proteinase 3, a protein found in certain white blood cells. It helps identify conditions like vasculitis, an inflammation of blood vessels.

Quick summary

["This test may help diagnose or monitor certain autoimmune diseases affecting blood vessels."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
89505-2
Short code
Proteinase3 Ab Ser Ql Line blot
Synonyms
Proteinase3 Ab Ser Ql Line blot
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Does This Test Measure?

The test looks for the presence of antibodies specific to Proteinase 3, a protein linked to a type of vasculitis called **granulomatosis with polyangiitis (GPA)** or **Churg-Strauss syndrome**. These antibodies are part of your immune system’s response and can indicate an ongoing inflammatory process in your blood vessels.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms like persistent sinus or lung infections, unexplained skin rashes, kidney problems, or other signs of vasculitis. It’s often used alongside other tests to confirm a diagnosis or assess disease activity.

How Is the Sample Collected?

A small amount of blood is drawn from a vein in your arm. The blood is sent to a lab for testing using a specialized line blot technique to detect the antibodies.

What Are Common Symptoms Linked to This Test?

Symptoms of vasculitis (which may be linked to PR3 antibodies) can vary widely but often include persistent sinus or lung infections, unexplained skin rashes, kidney issues, nerve pain, or swelling in the hands/feet. Some people may have no symptoms at all.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Understanding the Role of PR3 Antibodies

Short name

PR3 Antibody Screening/Confirmation

Frequently asked questions

How accurate is this test?
This test is highly specific for certain types of vasculitis but isn’t perfect. False positives or negatives can occur, so results are usually interpreted alongside other clinical findings, symptoms, and possibly additional tests.
What does a positive result mean?
A positive result strongly suggests the presence of PR3 antibodies, which may indicate vasculitis. However, further evaluation (like biopsies or other tests) is needed to confirm the diagnosis and guide treatment. Always discuss results with your doctor.
Can lifestyle changes affect this test?
No, this test measures antibodies in your blood, which are part of your immune system. While lifestyle factors (like diet or stress) can influence overall health, they don’t directly affect antibody levels detected by this test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy